The present invention relates to a method of resin molding and a resin molding machine.
In conventional resin molding machines for molding work pieces, e.g., semiconductor devices, the work pieces are clamped by a molding die, resin is melted and exerted in a pot, and cavities of the molding die are filled with the molten resin to mold the work pieces. When the cavities are filled with the resin, air in the cavities must be discharged. To discharge the air, an air vent is formed in a clamping member of the molding die. The air left in the cavities is discharged via the air vent.
In another way, the air left in cavities and resin paths of the molding die, which has clamped work pieces, is discharged by sucking air. The air is sucked by a vacuum unit. In this way, cavities, resin paths and pots, in which air is left, are air-tightly sealed, then the air left is discharged therefrom and the work pieces are molded with resin.
However, the method, in which air left in cavities, etc. is discharged and work pieces are molded with resin, has following disadvantages. A sealing member or members, which air-tightly seal the area including the cavities, etc., are provided on a parting face or faces of the molding die and projected therefrom. If a projecting length of the sealing member is too long, a cleaner cannot fully clean the molding die, so that disused resin is left in the molding die and badly influences the next molding process. And if the sealing member collides with cleaning brushes, the sealing member is damaged. On the other hand, if the projecting length of the sealing member is too short, the molding die can be well cleaned but sealing efficiency must be lower. Further, the molding die is always heated, so the sealing member is apt to be deteriorated by heat and sealing effect must be lower. By the lower sealing effect, the air in the molding die cannot be fully discharged, so that the air left badly influences molded products. As described above, the conventional methods cannot fully discharge air from the cavities, etc. of the molding die, and quality of the molded products are not satisfied.
Note that, in the case of molding a semiconductor chip connected to a substrate by flip-chip connection, a space (a connecting portion) between the chip and the substrate is filled with resin filler. In a conventional method, the connecting portion is filled by potting the filler, but it is difficult to correctly potting the filler into the connecting portion. To correctly fill the filler, the applicant of the present invention invented a method, in which the connecting portion is filled, with the resin filler, by a transfer molding machine (see Japanese Patent Gazette No. 11-274197). But, in the method executed by the transfer molding machine too, the air should be discharged from the area, in which air is left.
An object of the present invention is to provide a method of resin molding, in which air can be perfectly discharged from a specific area of a molding die including cavities, resin paths, pots, etc. so as to mold high quality products.
Another object of the present invention is to provide a resin molding machine executing the method of the present invention.
To achieve the objects, the present invention has following structures.
Firstly, the method of the present invention comprises the steps of:
covering a specific area of a molding die, in which air is left, with release film;
clamping a work piece and the release film between an upper die and a lower die of the molding die so as to air-tightly seal the specific area;
discharging the air from the sealed specific area; and
filling a molding section with resin.
Secondly, the resin molding machine of the present invention comprises:
a molding die having an upper die and a lower die, which clamp a work piece with release film;
a pot being formed in the molding die, the pot exerting and sending resin so as to mold the work piece;
a film feeding mechanism feeding the release film onto a parting face of at least one of the upper die and the lower die;
a sealing mechanism being provided to the parting face of at least one of the upper die and the lower die, the sealing mechanism enclosing and pressing the release film so as to air-tightly seal a specific area of the molding die, in which air is left, when the upper die and the lower die clamp the work piece and the release film; and
an air sucking mechanism being communicated to the specific area enclosed by the sealing mechanism, the air sucking mechanism discharging air from the molding die.
In the present invention, the specific area, e.g., a cavity, a pot, a resin path, of a molding die, in which air is left, is covered with the release film, and the work piece is clamped by the molding die together with the release film, so that the specific area can be air-tightly sealed. Further, the air left in the specific area can be compulsorily and perfectly discharged from the sealed specific area. Therefore, no air is involved in the resin for molding the work piece, so that no voids are formed in molded products and high quality products can be produced.